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Water heaters date-code guide

State Water Heaters serial number lookup

State is an A. O. Smith brand, and many residential tank and heat-pump water heaters share the parent company’s front-loaded year and production-week serial convention.

Parent
A. O. Smith Corporation
Common code
A widely used style begins with two digits for year and two digits for production week (YYWW).
Reviewed
August 8, 2026

Instant equipment lookup

Decode the manufacturing date

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Equipment type

Using A widely used style begins with two digits for year and two digits for production week (YYWW).

Type exactly what is printed. Spaces and dashes are ignored.

Optional: add model number for capacity cluesAdd model

Model decoding is labeled as a clue unless the exact format is documented.

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EQUIPMENT DATA
MODEL24ABC636A003
SERIAL5019X30312
WeekYear

See exactly how the code was read

SerialAtlas highlights the date characters, names the matching rule, and shows alternative interpretations when the code is ambiguous.

  • Current age calculated automatically
  • Confidence and rule source shown
  • Optional model-capacity clue

How to read a State Water Heaters serial number

A widely used style begins with two digits for year and two digits for production week (YYWW). SerialAtlas removes spacing and punctuation, then applies only the documented rule families mapped to State Water Heaters. The lookup remains in the browser.

Try this documented-style example0950A12345Load example

Equipment covered

  • gas tank water heaters
  • electric tank water heaters
  • heat-pump water heaters
  • selected commercial units

Commercial, imported, very old, specialty, and private-label equipment can use a different code. Confirm the full rating plate before accepting a result.

Where to find the rating plate

  • Upper or lower side of the tank jacket
  • Near the gas control valve on gas models
  • Behind an electrical access panel
  • Side or bottom edge of a tankless cabinet

Why more than one date can appear

Two-digit years and repeating letter cycles can point to more than one era. SerialAtlas ranks the plausible dates but keeps materially different alternatives visible. Label design, refrigerant, installation records, and product literature can resolve the era.

Source and verification

Inspector Handbook open reference data (CC BY 4.0). Independently implemented and reviewed August 8, 2026.

Open reference source

What this result does not prove

A manufacture date is not an installation date, warranty decision, recall match, condition assessment, or replacement recommendation. Confirm high-stakes decisions with the manufacturer or a qualified professional.